Integrated Design Analyses of Beyond Design Basis Accidents at VVER-1200, Including Fuel Severe Damage

A brief description and results of application of a VVER-1200 simulator intended for simulation of emergency processes in VVER-1200 reactors from the initial event to the processes of nuclear fuel severe damage, including simulation the internal and external stages of the accident, as well as for simulation the behaviour of the environment in the containment, are encapsulated in the report. The NPP simulator provides simulation of the main systems of a VVER-1200 NPP reactor plant and containment, safety systems including innovative passive safety systems, and control and protection systems. The calculation module for analysing the processes occurring in severe accident with the destruction of the core and reactor vessel is includes in the simulator mathematical model. The calculation models of the simulator are based on simulator technologies. It makes possible to carry out analysis of beyond design basis accidents in a reactor facility, both in real time and in an accelerated mode (5 - 7 times faster than real time). This makes it possible to use this simulator both for assessing the calculation safety justification of NPP projects and the effectiveness of actions provided in the accident management procedures, and for predicting the development of an emergency, as a tool for performing quick assessment and forecast calculations. Thus, a universal calculated tool has been developed that allows performing independent expert evaluation calculations as part of justification review of safety and predictive calculations in conditions of emergency training that complies with the provisions of IAEA Safety Standards Series No. GSR Part 4 (Rev. 1).